JP2016182556A - Waste water treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste water treatment apparatus capable of efficiently treating nitrate nitrogen and nitrite nitrogen in waste water over a long period.SOLUTION: A waste water treatment apparatus has: a denitrification tank in which waste water is supplied from a lower part and discharged from an upper part; a plurality of network containers installed at intervals from a lower side to an upper side of the denitrification tank; and a carrier stored in the network containers, for supporting denitrifying bacteria.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wastewater treatment apparatus for treating nitrate nitrogen and nitrite nitrogen in wastewater.

  When aquatic organisms are bred in an aquarium, ammonia nitrogen, phosphoric acid, etc. are generated from the excrement and residual food of the organisms, and the water quality deteriorates. Ammonia nitrogen is oxidized under aerobic conditions by a group of microorganisms collectively called nitrifying bacteria, and converted to nitrate nitrogen or nitrite nitrogen. Nitrate nitrogen and nitrite nitrogen cannot be removed by ordinary water treatment performed under aerobic conditions. Therefore, in order to prevent the influence on the breeding organisms due to the increase in the concentration of nitrate nitrogen or nitrite nitrogen, it is necessary to replace 5 to 10% of water in the water tank every day.

  In recent years, an aquarium has been established in an inland area away from the sea. Large aquariums with a water volume of 500 tons or more are often set up in aquariums, but in order to raise aquatic organisms that inhabit seawater in such large aquariums inland, It is necessary to transport or manufacture artificial seawater, which is very expensive. Moreover, since wastewater containing inorganic salts is released in large quantities as sewage, there are concerns about adverse effects on microorganisms in sewage treatment plants and organisms that inhabit freshwater such as rivers.

  Patent Document 1 proposes a closed-circulation type water treatment apparatus that can reduce or eliminate the amount of breeding water supplied. The water treatment apparatus of Patent Document 1 is provided with a nitrification tank and a denitrification tank in parallel, and oxidizes ammonia nitrogen and nitrite nitrogen to nitrate nitrogen by the action of nitrifying bacteria (autotrophic bacteria) in the nitrification tank ( Nitrification) and reduction of nitrate nitrogen and nitrite nitrogen to nitrogen (denitrification) by the action of denitrifying bacteria (heterotrophic bacteria) in the denitrification tank. If the water treatment apparatus of patent document 1 is used, since the raise of the density | concentration of nitrate nitrogen and nitrite nitrogen can be prevented, the frequency of water change can be reduced and water supply and waste water can be reduced significantly.

JP 2011-177619 A

  In the water treatment apparatus described in Patent Document 1, denitrifying bacteria are supported on a carrier and filled in a denitrifying tank. In the denitrification tank, nitrate nitrogen and nitrite nitrogen are reduced (denitrified) to form nitrogen, but nitrogen is insoluble in water, and nitrogen gas bubbles are generated. When these bubbles adhere to the carrier, the carrier floats and flows out, and there is a problem that the carrier is reduced and the denitrification performance is lowered. In addition, when the carrier is used for a long time, there may be a portion where the waste water in which the carriers adhere and agglomerate hardly flows, and a portion where the waste water without the carrier easily flows (hereinafter referred to as water pit). When water pits occur, there is a problem that waste water that flows in the water pits and does not come into contact with the carrier increases, and the waste water is discharged from the denitrification tank without being sufficiently denitrified. It is conceivable to physically stir with a stirring blade or the like in order to separate bubbles adhering to the carrier and to prevent water mitigation due to fluidization of the carrier. There is a new problem of exhaustion.

  An object of the present invention is to provide a wastewater treatment apparatus capable of efficiently treating nitrate nitrogen and nitrite nitrogen in wastewater over a long period of time.

1. A denitrification tank in which wastewater is supplied from the bottom and discharged from the top,
A plurality of mesh containers installed at intervals from the bottom to the top of the denitrification tank,
A carrier accommodated in the mesh container and carrying denitrifying bacteria;
A wastewater treatment apparatus characterized by comprising:
2. Among the plurality of mesh containers, the mesh container located at the lowest position has the largest capacity. The wastewater treatment apparatus described in 1.
3. 1. Waste water inside the denitrification tank is stirred intermittently. Or 2. The wastewater treatment apparatus described in 1.
4). Of the plurality of mesh-like containers, at least one of the mesh-like containers excluding the lowest mesh-like container has a recess extending in the vertical direction. ~ 3. The waste water treatment apparatus in any one of.
5. Among the plurality of mesh containers, at least one mesh container excluding the mesh container located at the lowest position has an inclined portion inclined with respect to the horizontal direction. ~ 4. The waste water treatment apparatus in any one of.
6). 1. A foam collecting member is provided between adjacent mesh containers. ~ 5. The waste water treatment apparatus in any one of.
7.1. ~ 6. A water tank for breeding aquatic organisms, wherein the water tank is connected to the wastewater treatment apparatus according to any one of the above, and water is circulated between the wastewater treatment apparatus.
8). The water in the tank where the aquatic organisms are bred ~ 6. A method for breeding aquatic organisms, characterized by being treated with the wastewater treatment apparatus according to any one of the above and circulating between the wastewater treatment apparatus and the water tank.

  In the wastewater treatment apparatus of the present invention, a plurality of mesh containers are installed at intervals from the bottom to the top of the denitrification tank, and there is a space between adjacent mesh containers. The waste water that has passed through the lower mesh container spreads and spreads in this space, and evenly collides with the entire surface of the carrier accommodated in the upper mesh container, thus preventing water mist from occurring in the mesh container. be able to.

  By increasing the capacity of the lowermost mesh container among the plurality of mesh containers, oxygen contained in the supplied wastewater can be quickly consumed. Oxygen is consumed by denitrifying bacteria in the carrier housed in the lowermost mesh container, so that the upper part of the lowermost mesh container becomes an anaerobic atmosphere, and the upper mesh container is The denitrification action by the denitrifying bacteria in the contained carrier is efficiently exhibited.

  By intermittently stirring the waste water inside the denitrification tank, the bubbles attached to the carrier can be separated. In addition, it is possible to prevent water from occurring due to the aggregation of the carrier. Since the waste water is agitated intermittently, it is possible to prevent the carrier contained in the mesh container from being rubbed and worn.

  By providing a recess in the side surface of at least one mesh container excluding the lowest mesh container among the plurality of mesh containers, bubbles are generated between the inner wall surface of the denitrification tank and the side surface of the mesh container. If a gap flowing upward is formed, bubbles that enter the inside of the mesh container can be reduced. Among the plurality of mesh-like containers, at least one mesh-like container excluding the lowest-most mesh-like container is provided with an inclined portion whose bottom surface is inclined with respect to the horizontal direction, and the upper part in the vertical direction of the inclined portion is mesh-like. By making it the center or edge of the bottom of the container, nitrogen bubbles generated in the lower mesh container flow along the bottom of the upper mesh container, and the bubbles penetrate into the upper mesh container. , It can be prevented from reattaching to the carrier. Furthermore, by providing the foam collecting member, it is possible to guide the bubbles so as not to enter the mesh-like container.

Sectional drawing of a wastewater treatment apparatus. The side view of the mesh-shaped container which has a recessed part in a side surface and a groove-shaped inclination part in a bottom face. The perspective view of the mesh container which has a recessed part in a side surface and a groove-shaped inclination part in a bottom face. The side view of the mesh-like container whose bottom face whole surface is an inclination part. The perspective view of the mesh-like container whose bottom face whole surface is an inclination part. The side view of a propeller-shaped foam collection member and a mesh container. The perspective view of a propeller-shaped foam collection member.

The present invention is described in detail below. In FIG. 1, sectional drawing of the waste water treatment apparatus of this invention is shown.
The wastewater treatment apparatus of the present invention is
A denitrification tank 1 in which wastewater is supplied from below and discharged from above,
A mesh-like container 2 that is installed in a plurality from the lower part to the upper part of the denitrification tank 1;
A carrier housed in the mesh container 2 and carrying denitrifying bacteria,
It is characterized by having.

  The wastewater treatment apparatus of the present invention only needs to have the denitrification tank 1, the mesh-like container 2, and the carrier, and can have other configurations as necessary in addition to these. For example, nitrification tanks that oxidize ammonia nitrogen and nitrite nitrogen with nitrifying bacteria to nitrate nitrogen, decomposition tanks that solubilize organic substances with acids, alkalis, enzymes, solubilizing bacteria, protein skimmers, filters, etc. Water temperature control devices such as physical filtration devices, heaters, coolers, heat exchangers, sterilization devices that kill pathogens with ultraviolet rays, ozone, chlorine, etc., oxygen supply devices that supply oxygen to the water after wastewater treatment, etc. can be provided .

  The denitrification tank 1 is not particularly limited as long as waste water is supplied from the lower part and discharged from the upper part, and may be either a sealed container or an open container. Here, the lower part means the bottom surface and the vicinity thereof, and the upper part means the upper surface and the vicinity thereof. In the denitrification tank 1, nitrate nitrogen and nitrite nitrogen contained in the wastewater are reduced (denitrified) by denitrifying bacteria to form nitrogen bubbles. By supplying wastewater from the lower part of the denitrification tank and discharging it from the upper part, the direction of the wastewater flowing inside the denitrification tank and the direction of buoyancy applied to the bubbles can be made the same, so the bubbles are efficiently discharged. be able to. The generated bubbles may be discharged together with the treated waste water, but it is preferable to provide the exhaust pipe 11 at the upper part of the denitrification tank and release the nitrogen gas from the exhaust pipe 11 in order to prevent liquid feeding failure due to the bubbles. In order to prevent the discharge of waste water from the exhaust pipe 11, it is preferable that the exhaust pipe 11 has a sufficient length.

The denitrification tank 1 may be used alone, or a plurality of denitrification tanks 1 may be connected in series or in parallel. Since the amount of wastewater treatment can be increased and the treatment capacity can be easily increased by adding the denitrification tank 1, it is preferable to connect them in parallel. The total volume of the denitrification tank 1 can be appropriately set according to the hydraulic residence time (HRT) and the nitrate nitrogen concentration to be targeted. If aquatic of using the water treatment water tank for breeding an organism, the nitrate nitrogen concentration 25NO ₃ ^- preferably in a -Nmg / L or less, 2% of the breeding water rearing water tank the total volume of the denitrification tank 1 The above is preferable.

  Inside the denitrification tank 1, a plurality of mesh-like containers 2 are installed at intervals from the lower part to the upper part. The number of mesh-like containers 2 installed in the denitrification tank 1 is not particularly limited. Moreover, the space | interval of a mesh container can be suitably determined according to the flow rate of HRT or waste water. The capacity of the plurality of mesh containers 2 may be the same or different, but as will be described in detail below, the mesh container 21 located at the lowermost position is 1. It is preferable to have a capacity of 2 times or more. The material for forming the mesh container 2 is not particularly limited, and a composite material such as a metal such as iron, aluminum, and stainless steel, a synthetic resin such as polystyrene and polypropylene, and a fiber reinforced plastic (FRP) can be used as appropriate. Since it does not rust and is lightweight, it is preferable to use synthetic resin or FRP.

  The net-like container 2 may have a net-like shape in which the bottom surface and the upper surface can pass waste water, and the side surface may or may not have a mesh. The surface of the mesh container 2 having the mesh may be formed by punching a large number of holes in a single plate material, or may be formed by joining a plurality of core materials. When forming from a core material, the cross-sectional shape of the core material is not particularly limited, and a circular shape, a square shape, or the like can be used as appropriate. When a mesh-like container is formed from a triangular, pentagonal, or tear-shaped core material in which the lower gap between adjacent core materials is narrower than the upper gap, a so-called wedge mesh can be formed. Foreign matter clogged in can be easily removed by flowing water from the opposite side.

  The cross-sectional shape of the mesh container 2 in the horizontal direction is not particularly limited as long as it can be accommodated in the denitrification tank 1. Moreover, the ring shape which has the hole penetrated in the center part may be sufficient. The cross-sectional shape in the horizontal direction of the mesh-like container 2 is preferably similar to the horizontal cross-sectional shape of the denitrification tank 1 and slightly smaller. By adopting such a shape, the amount of waste water passing through the gap between the inner wall surface of the denitrification tank 1 and the side surface of the mesh-like container 2 can be reduced, and the amount of waste water passing through the mesh-like container and contacting the carrier can be increased. Therefore, denitrification efficiency can be increased.

  The present invention is characterized in that a plurality of mesh-like containers 2 are installed at intervals from the lower part to the upper part of the denitrification tank 1. There is a space between the adjacent mesh containers 2, and the waste water that has passed through the lower mesh container spreads and spreads in this space, and uniformly strikes the entire surface of the carrier stored in the upper mesh container. Therefore, the wastewater treatment apparatus of the present invention can prevent the occurrence of water pits and prevent a decrease in contact efficiency between the wastewater and the carrier.

  A carrier carrying denitrifying bacteria is accommodated in the mesh container 2. The type of carrier used in the present invention is not particularly limited. For example, porous materials such as granulated sludge, porous glass, porous ceramic, coral sand, natural resin or synthetic resin sponge, gel, activated carbon, and nonporous materials such as natural rock and glass Can be used. Among these, granule sludge composed of the denitrifying bacteria themselves can be suitably used because of high processing efficiency and a compact denitrification tank.

  The carrier is accommodated in the mesh container 2 having a mesh smaller than the particle diameter of the carrier, or is accommodated in the mesh container 2 in a state of being accommodated in a net having a mesh smaller than the particle diameter of the carrier. For example, since the particle diameter of the granule sludge is about 2 mm, the mesh container or the mesh of the net that contains the carrier is preferably about 1 mm. Since the carrier is accommodated in a mesh container or net having a mesh smaller than the particle size of the carrier, the carrier does not leak from the mesh container or net. Therefore, even if bubbles adhere to the carrier, the carrier does not flow out of the denitrification tank 1.

  The carrier carries denitrifying bacteria. Denitrifying bacteria is a general term for nitrate-reducing bacteria, sulfur-oxidizing denitrifying bacteria, and the like that produce nitrogen by reducing nitrate nitrogen or nitrite nitrogen. Many of the denitrifying bacteria belong to facultative anaerobic heterotrophic bacteria that can act and grow under anaerobic conditions. In the present invention, sulfate-reducing bacteria that coexist with sulfur-oxidizing denitrifying bacteria are also included in the denitrifying bacteria. Sulfate-reducing bacteria produce sulfate ions and thiosulfate ions by reducing sulfates. Sulfur ions and thiosulfate ions are used for denitrification by sulfur oxidizing denitrifying bacteria. In the present invention, Thauera genus, Sedimenticola genus, Arcobactor genus and the like, which are generally known as denitrifying bacteria, can be used without particular limitation. The genus Thauera is an acetic acid-assimilating denitrifying bacterium and is also known as an aromatic compound-degrading bacterium.

  If the oxidation-reduction potential (ORP) of the denitrification tank is too low, hydrogen sulfide is generated. Therefore, it is preferable to adjust the oxidation-reduction potential (ORP) to a range of −300 (mV) to −100 (mV). In order to adjust the redox potential, the amount of waste water supplied to the denitrification tank and the amount of carbon source / electron donor supplied may be controlled.

  The denitrifying bacterium is supplied with a solubilized organic substance as a carbon source and an electron donor. The solubilized organic substance is desirably added so that the carbon ratio (C / N ratio) in the carrier is 1.0 to 3.0. In addition, when the amount of organic substances in water is insufficient, sodium acetate, acetic acid, methanol, glucose, or the like that serves as a carbon source / electron donor for denitrifying bacteria may be supplied. Of these, sodium acetate or acetic acid is preferred because it has little effect on the organism.

  Since most of the denitrifying bacteria belong to facultative anaerobic heterotrophic bacteria that can be activated and propagated under anaerobic conditions, the inside of the denitrifying tank 1 needs to be maintained in an anaerobic atmosphere. However, when waste water with a high dissolved oxygen concentration is supplied to the denitrification tank 1, the vicinity of the mesh container 21 at the bottom of the denitrification tank becomes an aerobic atmosphere, but in the aerobic atmosphere, the denitrifying bacteria consume oxygen and are active. Therefore, denitrification, which is metabolism in an anaerobic atmosphere, is not performed. Therefore, it is preferable that the mesh container 21 located at the lowermost part has a larger capacity than other mesh containers so that oxygen contained in the supplied wastewater can be quickly consumed. Specifically, it is preferable that the lowermost mesh container has a capacity 1.2 times or more than the second largest mesh container. The lowermost mesh container 21 has a large capacity, accommodates a large amount of carrier and consumes oxygen in the wastewater, so that the upper part of the lowermost mesh container 21 becomes an anaerobic atmosphere, The denitrification action by the denitrifying bacteria in the carrier accommodated in the mesh container located is efficiently exhibited.

  In this invention, it is preferable that the waste water inside a denitrification tank is stirred intermittently. The method for stirring the waste water inside the denitrification tank is not particularly limited. For example, a driving device 3 is provided for intermittently rotating, vibrating, or both of the mesh container 2, and the mesh container 2 is rotated. The waste water inside the denitrification tank may be stirred by causing either or both of vibrations. The vibration may be in any of a vertical direction, a horizontal direction, and an oblique direction, or a combination thereof. By intermittently stirring the waste water, the bubbles attached to the carrier can be separated. Since less energy is required to move the heavy mesh container containing the carrier, the mesh container is preferably rotated or vibrated in the vertical direction. Further, as described below, the waste water may be agitated in the space between adjacent mesh containers.

  Although it does not restrict | limit especially as the drive device 3, For example, the axis | shaft 4 which penetrates the center of the some mesh-like container 2 is provided, this axis | shaft 4 is rotated with a motor etc., or is combined with a gear, a cam, etc. Just vibrate at the same time. At this time, as described above, when the ring-shaped mesh-like container 2 having the center portion penetrated is used, it is easy to pass the shaft 4 through the center portion of the mesh-like container. It is preferable to provide a motor as the driving device 3 at the top and pass the shaft through the exhaust pipe 11 provided at the top of the denitrification tank because the structure can be simplified and the cost is low. In addition, when rotating the mesh container 2, it is preferable that the horizontal cross section is circular so that the denitrification tank 1 and the mesh container 2 can rotate.

  In the present invention, the waste water inside the denitrification tank is stirred intermittently. By intermittently stirring the inside of the denitrification tank, it is possible to prevent the carriers contained in the mesh container 2 from rubbing and wearing compared to the case of constantly stirring the inside of the denitrification tank. The interval at which the wastewater is stirred can be determined as appropriate according to the amount of nitrogen gas produced and the amount of nitrogen gas adhering to the carrier. Moreover, stirring may be performed regularly and may be performed irregularly.

  As described above, the shape of the mesh container 2 is not particularly limited, but the side surface of at least one mesh container excluding the mesh container 21 located at the lowest position of the plurality of mesh containers extends in the vertical direction. It is preferable to have the recessed part 5 which exists. A side view of the mesh-like container 2 having the recess 5 on the side surface is shown in FIG. 2, and a perspective view is shown in FIG.

  Since the mesh of the mesh container 2 is fine, bubbles generated in the mesh container 2 below do not immediately pass through the mesh on the bottom of the mesh container 2 above. A recess 5 is provided on the side surface of the mesh container, and a gap formed by the recess 5 is formed between the inner wall surface of the denitrification tank 1 and the side surface of the mesh container 2, so that the air bubbles once retained by the mesh on the bottom surface of the mesh container Air bubbles flowing upward from the gap and entering the inside of the mesh container 2 can be reduced. The shape and number of the recesses 5 are not particularly limited, but the ratio of the total area of the horizontal section of the recess 5 to the horizontal section of the denitrification tank is preferably 10% or less. If it is larger than 10%, too much waste water does not pass through the inside of the mesh container.

  Furthermore, it is preferable that the bottom surface of at least one mesh-like container excluding the lowest mesh-like container 21 among the plurality of mesh-like containers has an inclined portion 6 that is inclined with respect to the horizontal direction. By providing the inclined portion 6 on the bottom of the mesh-like container, it is possible to collect bubbles on the inclined portion 6 and combine the bubbles into large bubbles, making it difficult to pass through the mesh on the bottom of the mesh-like container. Further, by setting the upper portion of the inclined portion 6 as the end portion or the center of the bottom surface, the bubbles can be guided to the end portion or the center of the bottom surface along the inclination of the inclined portion 6. The shape and number of the inclined portions 6 are not particularly limited, and for example, a cone that is convex downward, a hemisphere that is convex downward, a cone that is convex upward, and a cone that is convex upward, The entire bottom surface may be an inclined portion, or one or a plurality of groove-shaped inclined portions may be formed, and only a part of the bottom surface may be the inclined portion.

  The mesh-like container shown in FIGS. 2 and 3 has a groove-like inclined portion 6 with the bottom end portion facing upward. In this mesh-like container, the bubbles that have reached the bottom end part float between the denitrification tank and the mesh-like container, so that bubbles entering the inside of the mesh-like container 2 can be reduced. 2 and 3, since the inclined portion 6 on the bottom surface and the concave portion 5 on the side surface are continuous, the bubbles can float more smoothly. The mesh container 2 is not limited to the one having both the inclined portion 6 and the recessed portion 5, and may have only the inclined portion 6.

FIG. 4 shows a side view of the mesh-like container 2 whose bottom surface has an upwardly convex conical shape and the entire bottom surface is the inclined portion 6, and FIG. 5 shows a perspective view.
4 and 5, the shaft 4 passing through the center of the mesh container 2 is a hollow tube, and has an opening 41 at a portion intersecting the bottom surface of the mesh container on the side of the shaft. 4 and 5 in which the entire bottom surface is an inclined portion, bubbles collected at the center of the bottom surface are taken into the shaft 4 from the opening 41 provided in the shaft and pass through the inside of the mesh container. Without being discharged out of the denitrification tank 1. In addition, the method of guiding the air bubbles guided to the center of the bottom face upward without passing through the inside of the mesh container is not limited to this. For example, a ring-shaped container is used as the mesh container 2, Bubbles may be passed upward from the center.

  A foam collecting member 7 may be provided between adjacent mesh containers 2. The material for forming the foam collecting member 7 is not particularly limited, and composite materials such as metals such as iron, aluminum, and stainless steel, synthetic resins such as polystyrene and polypropylene, and fiber reinforced plastics (FRP) can be used as appropriate. Since it does not rust and is lightweight, it is preferable to use synthetic resin or FRP. The foam collecting member 7 may not be able to pass water. However, when the waste water flows strongly from the gap of the foam collecting member 7, water mist tends to occur in the portion where the waste water concentrates and collides, so the foam collecting member 7 It is preferable that it can pass. As a material through which water can pass, the same material as that of the mesh container can be used.

  The shape of the foam collecting member 7 can be used without particular limitation as long as the bubbles can be combined to form large bubbles. For example, a downwardly convex cone, a downwardly convex hemisphere, an upwardly convex cone, an upwardly convex cone, a propeller shape, an upwardly convex fan shape, and the like can be given.

  A side view of the propeller-shaped foam collecting member 7 fixed to the shaft 4 and the mesh container 2 is shown in FIG. 6, and a perspective view of the propeller-shaped foam collecting member 7 fixed to the shaft 4 is shown in FIG. In such a configuration, when the shaft 4 is rotated, the wastewater can be strongly stirred by the propeller-shaped foam collecting member 7. For this reason, bubbles adhering to the carrier can be further separated, and aggregation of the carriers can be prevented. At this time, a ring-shaped container may be used as the mesh-shaped container 2, and the ring-shaped mesh-shaped container and the shaft 4 may be connected or may not be connected.

  Bubbles collected by the foam collecting member 7 and coalesced to become larger do not easily pass through the mesh on the bottom of the upper mesh container. Further, in order to reduce the intrusion of the bubbles collected by the foam collecting member into the inside of the mesh container, the bubbles collected by the foam collecting member are located near the bottom end of the mesh container, the concave portion 5 and the inclined portion 6. It is preferable to surface.

  The wastewater treatment apparatus of the present invention can be used for treatment of wastewater containing nitrate nitrogen and nitrite nitrogen. For example, it can be used for wastewater treatment in a sewage treatment plant, wastewater treatment in a livestock farm, water treatment in a tank for breeding aquatic organisms, and the like. There are no particular restrictions on the type of aquatic organisms that are bred in a water tank that performs water treatment with the wastewater treatment apparatus of the present invention. Crustaceans such as crustaceans, sea anemones, jellyfish and corals, echinoderms such as sea urchins, sea cucumbers and starfish, amphibians such as frogs and salamanders, reptiles such as turtles, snakes and crocodiles, birds such as penguins and tufted puffins, otters and sea lions , Mammals such as sea otters, fur seals, dugongs, manatees and dolphins. It can also be used to breed both aquatic organisms that inhabit freshwater and aquatic organisms that inhabit seawater.

  By using the wastewater treatment apparatus of the present invention for water treatment in aquatic organism breeding tanks, the frequency of water exchange and replenishment can be reduced. Especially when used for water treatment of aquatic organisms breeding tanks that inhabit seawater, it can greatly reduce the transport of seawater or the production of artificial seawater and reduce the amount of wastewater containing inorganic salts to the sewage. it can. Furthermore, it is possible to suppress the growth of green algae and the like that nourish nitrate nitrogen and nitrite nitrogen, and maintain the water tank in a state suitable for viewing.

DESCRIPTION OF SYMBOLS 1 Denitrification tank 11 Exhaust pipe 2 Reticulated container 21 Reticulated container 3 located in the lowest part Drive apparatus 4 Shaft 41 Opening 5 Recessed part 6 Inclined part 7 Foam collecting member

Claims (8)

A denitrification tank in which wastewater is supplied from the bottom and discharged from the top,
A plurality of mesh-like containers installed at intervals from below to above the denitrification tank;
A carrier accommodated in the mesh container and carrying denitrifying bacteria;
A wastewater treatment apparatus characterized by comprising: The wastewater treatment apparatus according to claim 1, wherein the lowermost mesh container has the largest capacity among the plurality of mesh containers. The wastewater treatment apparatus according to claim 1 or 2, wherein the wastewater inside the denitrification tank is intermittently agitated. The side surface of at least one mesh-like container excluding the lowest mesh-like container among the plurality of mesh-like containers has a recess extending in the vertical direction. The waste water treatment device according to crab. The bottom surface of at least one mesh container excluding the mesh container located at the lowest position among the plurality of mesh containers has an inclined portion inclined with respect to the horizontal direction. The waste water treatment apparatus in any one of. The wastewater treatment apparatus according to any one of claims 1 to 5, further comprising a foam collecting member between the adjacent mesh containers. An aquatic organism breeding tank connected to the wastewater treatment apparatus according to any one of claims 1 to 6, wherein water is circulated between the wastewater treatment apparatus. An aquatic organism characterized in that the water in the aquarium in which aquatic organisms are bred is treated with the wastewater treatment apparatus according to any one of claims 1 to 6 and circulated between the wastewater treatment apparatus and the aquarium. Breeding method.

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